C# erase graphics using list

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C#

I have a function that doesn't always work. When the mouse left button is pressed and held and you drag over a graphic it will remove the points stored in a 2D list and redraw the other graphics. It works fine when setting it to the MouseUp Event m, but when invoked in the MouseMove event it will work if I ferociously hover over a graphic it will eventually remove it. Could it be an issue with the loop not fast enough??

private void Canvas_Panel_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {

        if (iamPainting)
        {
            Pen p = new Pen(Color.Black, float.Parse("2"));
            g.DrawLine(p, new Point(initX ?? e.X, initY ?? e.Y), new Point(e.X, e.Y));
            Lines2[theSize].Add(new Point(initX ?? e.X, initY ?? e.Y));
            Lines2[theSize].Add(new Point(e.X, e.Y));
        }
        else if (isErase)
        {
            Console.WriteLine("Erase: " + e.X.ToString() + " " + e.Y.ToString());
            int indexToRemove = 0;
            Boolean timetoBreak = false;
            for (int i = 0; i < Lines2.Count; i++)
            {
                for (int i2 = Lines2[i].Count - 1; i2 > 0; i2--)
                {
                    if (e.X == Lines2[i][i2].X && e.Y == Lines2[i][i2].Y)
                    //if (e.X >= Lines2[i][i2].X - 2 && (e.X + 2) <= Lines2[i][i2].X + 2 && e.Y >= Lines2[i][i2].Y - 2 && (e.Y + 2) <= Lines2[i][i2].Y + 2)
                    {
                        indexToRemove = i;
                        timetoBreak = true;
                        break;
                    }
                    if (timetoBreak)
                        break;
                }
            }
            if (timetoBreak)
            {
                Lines2.RemoveAt(indexToRemove);
                theSize -= 1;
                Canvas_Panel.Refresh();
            }
        }
        initX = e.X;
        initY = e.Y;
    }
}

What I have tried:

I've tried various loops, using different events but nothing really works.